linux-kernel - [PATCH v2 10/17] dmaengine: dma-jz4780: Add missing residue DTC mask

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Message-Id: <20180718182023.8182-11-paul@crapouillou.net>
Date:   Wed, 18 Jul 2018 20:20:16 +0200
From:   Paul Cercueil <paul@...pouillou.net>
To:     Vinod Koul <vkoul@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paul.burton@...s.com>,
        James Hogan <jhogan@...nel.org>,
        Zubair Lutfullah Kakakhel <Zubair.Kakakhel@...tec.com>
Cc:     Mathieu Malaterre <malat@...ian.org>,
        Daniel Silsby <dansilsby@...il.com>,
        Paul Cercueil <paul@...pouillou.net>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mips@...ux-mips.org
Subject: [PATCH v2 10/17] dmaengine: dma-jz4780: Add missing residue DTC mask

From: Daniel Silsby <dansilsby@...il.com>

The 'dtc' word in jz DMA descriptors contains two fields: The
lowest 24 bits are the transfer count, and upper 8 bits are the DOA
offset to next descriptor. The upper 8 bits are now correctly masked
off when computing residue in jz4780_dma_desc_residue(). Note that
reads of the DTCn hardware reg are automatically masked this way.

Signed-off-by: Daniel Silsby <dansilsby@...il.com>
Tested-by: Mathieu Malaterre <malat@...ian.org>
---
 drivers/dma/dma-jz4780.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

 v2: No change

diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
index 3c9d3952e23a..fa926de082ba 100644
--- a/drivers/dma/dma-jz4780.c
+++ b/drivers/dma/dma-jz4780.c
@@ -614,7 +614,8 @@ static size_t jz4780_dma_desc_residue(struct jz4780_dma_chan *jzchan,
 	residue = 0;
 
 	for (i = next_sg; i < desc->count; i++)
-		residue += desc->desc[i].dtc << jzchan->transfer_shift;
+		residue += (desc->desc[i].dtc & 0xffffff) <<
+			jzchan->transfer_shift;
 
 	if (next_sg != 0) {
 		count = jz4780_dma_chn_readl(jzdma, jzchan->id,
-- 
2.11.0